I was looking for a readalike for Mary Roach's Bonk: The Curious Coupling of Science and Sex for me to read, and, surprisingly (and some might say unfortunately), found my most promising leads in the Amazon.com "customers also bought..." section.
I think the appeal of Bonk is, in order of importance, sex, humor, science. I stumbled upon a Library Journal article on nonfiction readers' advisory, which sort of confused me more, but gave me allowance to put weight into subject (as opposed to the RA fiction concept that the plot isn't that important). In brief, in addition to the regular appeal elements, nonfiction is also affected by narrative, subject, and learning/experiencing.
Bonk's narrative is nonlinear, but definitely strong. Roach becomes a character, a friendly tour guide, who shares the details of the clothes, work environs, and personalities of the researchers she visits, and even employs dialog. All these help strengthen the narrative. Her self-aware, gently mocking humor speaks to the 13-year-old in us all who giggles when some says "do it". The subject holds the strongest appeal; readers want to learn about sex, and there aren't that many places to do it. The science details and strong narrative will attract those who don't want a straight-up how-to guide to orgasms.
One's first readalike thought may be Roach's previous books, science titles for general readers on dead bodies (Stiff) and ghosts (Spook). I think that would be wrong. Readers will pick up those for the science, but someone attracted to Bonk on the shelf is grabbing it for the good stuff--sex.
Here's my mini-list of nonfiction Bonk readalikes
Pornology by Ayn Carillo-Gailey
America Unzipped by Brian Alexander
How Sex Works by Sharon Moalem
Sex in History by Reay Tannahill
Sex in History is the only one of these I'm seeking out to read--I've already read Pornology, which has less science than Bonk but plenty of humor and sex; the other two on the list received so-so reviews. On a limb, I'll also add in fiction, Chemistry for Beginners by Anthony Strong, which publishes in Sept. There's not much info online yet, but a sneak peek at the 7/15 Library Journal review reveals it to feature science, sex, and humor (although romance is a big part of its appeal, so readers be warned).